1. What is Back Sight?

Back Sight is the sight or reading taken towards the back or towards a known elevation in surveying. It is used to establish the height of instrument and calculate reduced levels of unknown points.

2. How Does the Calculator Work?

The calculator uses the Back Sight formula:

Where:

• \( BS \) — Back Sight (m)
• \( HI \) — Height of Instrument (m)
• \( RL \) — Reduced Level (m)

Explanation: The formula calculates the back sight reading by subtracting the reduced level from the height of instrument.

3. Importance of Back Sight Calculation

Details: Accurate back sight calculation is crucial for establishing accurate bench marks and transferring elevations in surveying work. It forms the foundation for leveling operations and ensures precise elevation measurements across a survey area.

4. Using the Calculator

Tips: Enter height of instrument and reduced level in meters. Both values must be valid positive numbers. The calculator will compute the back sight reading.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between back sight and fore sight?
A: Back sight is taken on a point of known elevation, while fore sight is taken on a point whose elevation is to be determined.

Q2: When should back sight measurements be taken?
A: Back sight readings should be taken at the beginning of each instrument setup and whenever the instrument is moved to a new position.

Q3: What are typical values for back sight?
A: Back sight values typically range from 0.5 to 3.0 meters, depending on the instrument height and ground elevation.

Q4: Are there limitations to this calculation?
A: This calculation assumes proper instrument calibration and leveling. Environmental factors like refraction and temperature may affect accuracy in precise surveying.

Q5: How does back sight relate to height of collimation?
A: Height of collimation (or height of instrument) is calculated by adding back sight to the known reduced level of the benchmark.